On December 18, 2018, NASA’s Voyager 2 entered interstellar space while traveling at 38,000 miles per hour. Now over 12 billion miles/20 billion kilometers from Earth, Voyager 2 was reckoned by NASA engineers to have enough power to operate its five most basic instruments—such as its ability to contact Earth—until later this year.
For Voyager 2, an eternal darkness is imminent.
Or, at least, it was until engineers this week figured out a way to extend its life through 2026.
Voyager 2, like its sister spacecraft Voyager 1, are nuclear-powered. They use radioisotope thermoelectric generators (RTGs), which convert heat from decaying plutonium into usable electricity. Trouble is, that power dwindles.
Over the 46 years since they launched, engineers have had to switch-off heaters and other systems that are not essential to keeping the spacecraft flying.
Having run out of options for saving power, the engineers have now come up with a way of using a small reserve of power set aside for a safety mechanism designed to protect the instruments in case the spacecraft’s voltage changes.
“Variable voltages pose a risk to the instruments, but we’ve determined that it’s a small risk, and the alternative offers a big reward of being able to keep the science instruments turned on longer,” said Suzanne Dodd, Voyager’s project manager at JPL. “We’ve been monitoring the spacecraft for a few weeks, and it seems like this new approach is working.”
For Voyager 1, its fate is on the back-backer, having had a malfunction decades ago that killed-off one of its scientific instruments. Consequently it’s had a little bit more power to play with, but next year could see the same technique used to eek out its life, too.
Voyager 2 was the star of NASA’s Grand Tour mission of the late 1970s, photographing Jupiter, Saturn, Uranus and Neptune. As it left the inner solar system in 1990 it snapped the iconic Pale Blue Dot image.
Having left the solar system Voyager 1 and 2 recently also exited the heliosphere, the protective bubble of solar wind—particles and magnetic fields created by the Sun—and entered the heliopause, where the hot solar wind meets the cold of interstellar space.
In about 40,000 years, Voyager 2 will pass 1.7 light-years from the star Ross 248. In about 296,000 years it will pass 4.3 light-years from Sirius, the “Dog Star,” the brightest star in our night sky.
Wishing you clear skies and wide eyes.